Stricter emission requirements and increased performance requirements for internal combustion engine turbochargers continue to drive technological advancements in turbocharger design. One area of potential improvement is in wastegate design. Wastegate actuation system designs that provide for faster or stronger actuation allow for more accurate control of a wastegate, and thus more efficient turbocharger operation. Wastegate actuation system designs that provide for an improved actuation strength (for a given actuator size or weight), allow for smaller and lighter actuators to be used, as well as potentially offering for more accurate operation in extreme operating conditions.
Actuation systems using an electric actuator (e.g., a DC motor) can provide for fast and powerful actuation, but electric actuators have a number of drawbacks. Among those drawbacks are a larger package size and a lower maximum operating temperature than a comparable pneumatic system. For example, a typical electric actuator operating temperature is limited to 160 degrees centigrade, whereas a typical pneumatic actuator has a continuous operating temperature of up to 180 degrees centigrade. Moreover, at its maximum operating temperature, a DC motor has to be de-rated, i.e., the motor duty must be reduced (e.g., by 50%) to avoid the stator windings from exceeding their rated limit.
Accordingly, there has existed a need for a fast, powerful and compact wastegate actuation system that can operate effectively in the hot environment of a turbocharger without having to be de-rated. Preferred embodiments of the present invention satisfy these and other needs, and provide further related advantages.